Large slope failure along Crystal Creek, Teton County.
Large slope failure along Crystal Creek,
Teton County. Photo: Seth Wittke, WSGS

Landslides in Wyoming

Landslides, also known as mass wasting, are the downward movement of rock caused by gravity and occur when a slope becomes unstable. Rock falls, debris flows, slumps, lateral spread, and creep are all types of landslides. Landslides can cause considerable damage. They can damage or destroy roads, pipelines, structures, and utility lines. Landslides can also temporarily block rivers with earthen dams, which when over topped by backed up water can cause flash-flooding downstream. The WSGS has mapped more than 30,000 landslides in Wyoming, and maintains the database of these locations. To view the database, click here. To view a landslide map of Wyoming, click here.

Type of Landslides

  • Debris Flow: A mass of loose, water-laden and poorly sorted debris of fragmented rock, soil, and mud that surges down a slope in response to gravitational processes. Debris flows can be triggered by heavy rainfall or rapid snowmelt or by other landslides.
  • Falls:Unexpected release of rock or coarse material from a steep slope.
  • Topples: Comparable to falls, but the primary motion involves forward rotation and mass movement of rock or debris out of a slope face.
  • Creep: Slow movement a material down a slope.
  • Rotational (slump): Block of material moving down a slope along a concave surface.
  • Translational: Block of material moving down-slope that occurs along a distinctive surface of weakness (soil horizon, bedding or fault) or parallel to the ground surface.

Landslide Diagram
Rotational Landslide. Diagram by Jim Rodgers.

Download Map
A WSGS landslide map of the northern portion of the Wapiti 7.5 Minute Quadrangle, Wyoming. Download Map. Private residence built on the toe of a large landslide complex, near Wapiti, Wyoming. Photo: Seth Wittke, WSGS.

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